The present invention relates to improved liquid copolymeric reactive organosiloxane resins.
Useful liquid copolymeric organosiloxane resins are disclosed in U.S. Pat. No. 4,310,678, issued Jan. 12, 1982 to Blizzard et al. and assigned to the assignee of the present invention. The resins of Blizzard et al. comprise the reaction product of a particular resin and an organohydrogensiloxane. The resins of Blizzard et al. are useful as reactive components in curable silicone compositions such as coatings and elastomers.
Unfortunately, the resins of Blizzard et al. are sometimes excessively reactive with the other components of a curable silicone composition, which can lead to inconveniently short working times for the curable composition. This problem is especially acute when the curable compositions are catalyzed by tin compounds. Additionally, coating compositions containing the resins of Blizzard often have less than ideal adhesion to the substrates to which they have been applied.
The present invention deals with an improvement on the resins of Blizzard. Surprisingly, when the resins of Blizzard are reacted with a compound selected from acyloxysilanes, alkoxysilanes, oximosilanes, and acyl halides, improvements in adhesion and/or working time are found in curable compositions incorporating these resins.